The main components of a drive train of a motor vehicle are a drive aggregate and a transmission. A transmission converts torque and rotational speeds and thereby sets the tractional force passed by the drive aggregate. The present invention here concerns a method for operating a drive train which comprises at least a transmission which has, as the drive aggregate, a hybrid drive including a combustion engine and an electric motor, wherein a clutch is positioned between a combustion engine and an electric motor of the hybrid drive, and wherein the drive train also has a transmission internal starting element or a transmission external starting element. Such a drive train is also referred to as a parallel hybrid.
In such a parallel hybrid, there exists the difficulties of achieving a fuel efficient, comfortable, and low loss crawling start. This crawling start is meant as an operating mode of the drive train at which the drive train turns when the accelerator pedal or the throttle, respectively, is not operated. A crawling start has to be differentiated from a start at which the accelerator pedal or throttle, respectively, of the drive train is operated.
Based on this, the present invention takes the above problem and creates a novel method for operating a drive train which comprises of a transmission and a hybrid drive.